My 1973 Atomic 4 engine failed to start. I assumed that it had to be either no spark or no fuel.Took a spare plug, pulled off a wire off a plug on the engine and attached it to the spare plug. Holding the spare plug with plyers, and making sure there is no gas odor, I tried starting the engine. There was spark. I reattached the wire and assumed that it had to be fuel.There's a small bowl just prior to the carborator that's supposed to collect contaminates before they get to the carb. I put a rag under the bowl and unscrewed the bowl. I emptied the gas into a container and noticed a lot of white power at the bottom of the bowl. I figured that the carb was contaminated and blocked. I removed the carb and had my mechanic clean and check it out. I reinstalled the carb, cleaned and reinstalled the bowl, and started the engine. It worked!!!! I just purchased a water separator filter to install in my gas line hopefully to prevent this from happening again.I didn't know too much about Atomic 4 engines before since I just bought the boat, but I sure am having fun learning.